Aqueous Polymer Solution Mixing for EOR Injectivity
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Solution Overview
Problem
Existing methods for preparing aqueous polymer solutions for enhanced oil recovery (EOR) face challenges such as slow inversion of water-in-oil emulsions and poor injectivity through porous structures, limiting their utility due to high filtration ratios and plugging issues.
Innovation Solution
A single stage mixing process is employed to combine a liquid polymer composition with an aqueous fluid, applying specific mixing energy to achieve a filter ratio of 1.5 or less, using various LP compositions and in-line mixer configurations to ensure efficient polymer dispersion and flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water-in-oil emulsions are used to provide polymer solutions, then polymer dissolution is simplified, but inversion is slow and filterability is poor
Solution Approach 1:
The patent applies preliminary action by pre-dissolving the polymer in the dispersed aqueous phase during emulsion formation. The polymer is incorporated into the internal aqueous phase before emulsion creation, so that when inversion occurs, the polymer is already in solution and does not require additional dissolution time. This resolves the contradiction by preparing the polymer in advance in a state that enables both easy dissolution and rapid inversion.
2Strength
If water-in-oil emulsions are used, then polymer thickening properties are maintained, but injectivity through porous structures is poor due to plugging
Solution Approach 1:
The patent applies parameter changes by controlling the emulsion droplet size distribution and polymer concentration within the dispersed phase. By optimizing these parameters, the inverted emulsion achieves a balance between maintaining sufficient viscosity for thickening and having small enough droplet sizes to pass through porous structures without plugging. This resolves the contradiction by adjusting physical parameters to simultaneously achieve both thickening strength and injectivity.
3Adaptability or versatility
If existing water-in-oil emulsions are inverted using aqueous medium with salts, then EOR application requirements are met, but inversion efficiency is poor
Solution Approach 1:
The patent applies the intermediary principle by using a surfactant system that facilitates the inversion process. The surfactant acts as a mediator between the oil and aqueous phases, reducing interfacial tension and enabling efficient emulsion inversion even in the presence of salts. This resolves the contradiction by introducing a chemical intermediary that enhances inversion efficiency while maintaining compatibility with EOR application requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces aqueous polymer solutions with improved filterability and injectivity, enabling effective use in EOR applications without plugging issues, as demonstrated by reduced filtration ratios and steady-state pressure drops during oil recovery.
Implementation Method 1
The single stage mixing process can comprise applying a specific mixing energy of at least 0.10 kJ/kg to the LP composition and the aqueous fluid
Implementation Method 2
The water-in-oil emulsions can then be inverted to form oil-in-water emulsions at their time of use
Data Source
AI summary
Provided herein are liquid polymer (LP) compositions comprising a synthetic (co)polymer (e.g., an acrylamide (co)polymer), as well as methods for preparing aqueous polymer solutions by combining these LP compositions with an aqueous fluid. The resulting aqueous polymer solutions can have a concentration of a synthetic (co)polymer (e.g., an acrylamide (co)polymer) of from 50 to 15,000 ppm, and a filter ratio of 1.5 or less at 15 psi using a 1.2 μm filter. Also provided are methods of using these aqueous polymer solutions in oil and gas operations, including enhanced oil recovery.